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Biomedical subjects

Andreas D Rabavilas

Publications and source records attributed to Andreas D Rabavilas.

9 recordsLinked to original sources
PubMed2006

Changes in LORETA and conventional patterns of P600 after steroid treatment in multiple sclerosis patients.

OBJECTIVE: The P600 component of event-related potentials (ERPs) reflecting the 'rule-governed sequence of information processing', has been associated with multiple sclerosis (MS)-related cognition. The present study aimed at examining the effects of methylprednisolone treatment in MS patients on cognition as reflected by the low-resolution brain electromagnetic tomography (LORETA) of the P600 as well as its conventional constituents (amplitudes and latencies) recorded during a working memory (WM) test. METHOD: A paired LORETA comparison was performed in the P600 component of ERPs elicited during a (WM) test in 18 MS patients suffering from the relapsing-remitting form, before and after 1 week treatment with methylprednisolone. The P600 component was also evaluated in 16 healthy controls matched to the patients on age and educational level. RESULTS: When pre- and post-treatment recordings of LORETA were compared all patients as a group showed significantly different patterns of current density activation located at right frontal lobe. The treatment was accompanied by an increase of the amplitude of P600 at the right frontoparietal area. In the post-treatment phase the patients exhibited significant improvement of the memory performance as compared to themselves before treatment. As a result both the P600 amplitudes and memory performance at post-treatment were closer to those exhibited by normal controls. CONCLUSION: These findings support the notion that steroid treatment in relapsing-remitting MS patients, may exert a beneficial effect in 'rule-governed sequence of information processing'.

Acoustic Stimulation↗
PubMed2006

Acute mobile phone effects on pre-attentive operation.

There is a debate whether electromagnetic field (EMF) emitted by mobile phones (MP) have an effect on cognitive functions. Since the auditory P50 component of event-related potentials (ERPs) reflects pre-attentive processing and working memory (WM) operation, the present study was designed to investigate whether the exposure to MP-EMF affects the patterns of the P50 component of ERPs elicited during a WM test. The P50 elicited during a WM task and evoked by two warning stimuli low and high frequency (500 and 3000 Hz) has been assessed in 19 normal subjects (10 women and 9 men) both without and with exposure to a 900 MHz signal, emitted by a dipole antenna placed near the subjects. Results showed that the presence of MP-EMFs induced statistically significant increase in the amplitude of P50 evoked by the low frequency stimuli, at Fp1 and O1 electrode leads as compared to themselves without MP-EMF exposure. In contrast the exposure to MP-EMFs revealed statistically significant decrease of the amplitude of P50 evoked by the high frequency stimuli, at Fp1 electrode lead as compared to themselves without MP-EMF exposure. These findings provide evidence that the MP-EMF emitted by mobile phone affect pre-attentive information processing as it is reflected in P50 evoked potential. The basis of such an effect is unclear, although several possibilities exist and call for potential directions of future research.

Adult↗
PubMed2006

Abnormal auditory N400 in a case of zolpidem dependence, during a working memory test.

Zolpidem is a GABA (A) agonist, which is indicated for the short-term management of insomnia. Recent research provide evidence suggesting that zolpidem produces spatial working memory (WM) deficits and dependence; however, the underlying mechanisms of these effects are unknown. Since the auditory N400 component of event-related potentials (ERPS) is considered as an index of memory use of context processing, the present study focused on N400 waveform of ERPs elicited during a WM task in a case suffering from zolpidem dependence. The patterns of N400 waveform of this case were compared to the patterns obtained from healthy controls. This comparison revealed that zolpidem dependence is accompanied by reduced amplitudes located at posterior brain areas and diffuse prolongation of N400. These findings may indicate that zolpidem dependence manifests alterations with regard to the memory use of context processing, involving or affecting a wide-ranging network of the brain's structures.

Adult↗
PubMed2005

Association between hostility and plasma total homocysteine concentrations in a general population sample.

OBJECTIVE: The present study focuses on testing the association of hostility with plasma homocysteine levels in a general population sample. METHOD: Four hundred and ten healthy adults (200 men and 210 women), participating in a health survey in Greece, had blood samples taken for homocysteine concentrations and also completed a multidimensional hostility questionnaire, assessing direction of hostility ('extra- and intropunitive') as well as total hostility and its ingredients, i.e. urge to act out hostility, criticism of others, delusional hostility, self-criticism and delusional guilt. Multivariate relationship was tested between hostility components and homocysteine, after statistically controlling for potential confounders such as age, gender, educational status, smoking and body mass index. RESULTS: Total hostility, delusional guilt as well as extrapunitive direction of hostility were positively related to homocysteine levels. Self-criticism was negatively related to homocysteine. CONCLUSION: The study provides further evidence that particular dimensions of hostility are associated with increased plasma homocysteine levels, thus deserving a place within the spectrum of the coronary heart disease risk factors.

Adult↗
PubMed2005

Neuropsychological correlates of Greek alcoholic patients who report memory disturbances.

We studied 40 male and 37 female (M age=63 yr.) Greek alcoholic patients and an equal number of control subjects. Both groups were evaluated with the Mini-Mental State Examination, the Syndrome Short Test, the Verbal Fluency Test (Category & Letter), the Clock Test, and the Digit Span (Forward and Backward from the Wechsler Adult Intelligence Scale-Revised). Alcoholic patients had statistically significant lower scores on MMSE, Verbal Fluency Test, and Digit Span, and higher scores on the Syndrome Short Test, while positive correlations were found among MMSE, Verbal Fluency Test, Clock Test, Digit Span-Backward, and age. These findings point to frontal lobe dysfunction in Greek alcoholic patients which is not different from that shown in patients from diverse ethnic and cultural backgrounds.

Adult↗
PubMed2004

Gender related differences on the EEG during a simulated mobile phone signal.

The present study investigated the gender-related influence of electromagnetic fields (EMF), similar to that emitted by mobile phones, on brain activity. Ten women and nine men performed a short memory task (Wechsler test), both without (baseline) and with exposure to a 900 MHz signal. The EEG energy of the total waveform and the alpha, beta, delta and theta; rhythms were calculated from the recordings of 15 scalp electrodes. Baseline EEG energy of males was greater than that of females, while exposure to EMF decreased EEG energy of males and increased that of females. Memory performance was invariant to EMF exposure and gender influences. These findings indicate that EMF may exert a gender-related nfluence on brain activity.

Adult↗
PubMed2004

Long-term abstinence syndrome in heroin addicts: indices of P300 alterations associated with a short memory task.

Attentional deficits have been implicated in the pathophysiology of opioid addicts. The P300 component of event-related potentials (ERPs) is considered as a manifestation of attentional operations. The authors' goal was the comparison of P300 elicited during a short memory test between subjects with prolonged heroin abstinence and current heroin users as well as healthy controls. The P300 component was evaluated during the anticipatory period of a short memory task in 20 patients characterized by a past history of opioid dependence (6 months abstinence), in 18 current heroin users and in 20 healthy comparison subjects, matched for age, sex and educational level. Abstinent heroin addicts exhibited significant reduction of P300 amplitude at central frontal region, relative to the other two groups. The findings are discussed in connection to the aim of identifying psychophysiological indices, addressing issues in opioid use disorders, and suggest that knowledge about cognitive operations, such as those reflected by P300 component, could provide further insight into psychophysiological mechanisms underlying the long-term abstinence state of heroin addicts.

Acoustic Stimulation↗
PubMed2003

Abnormal P600 in obsessive-compulsive disorder. A comparison with healthy controls.

Recently, the P600 component of the event-related potential (ERP), a waveform that is thought to be generated and/or modulated by the anterior cingulate gyrus and basal ganglia has been considered as an index of second pass-parsing processes of information processing, having much in common with working memory (WM) operation. Moreover, dysfunction of these brain structures as well as WM deficits have been implicated in the pathophysiology of obsessive-compulsive disorder (OCD). The present study is focused on P600 elicited during a WM test in OCD patients compared with healthy controls. Twenty drug-free OCD patients and an equal number of normal subjects matched for age, sex and educational level were studied via a computerized version of the Wechsler digit span test. Auditory P600 was measured during the anticipatory period of this test. The patient group, as compared with healthy controls, showed significantly enhanced amplitudes of P600 at the right temporoparietal area and prolonged latencies at the right parietal region. Moreover, the memory performance of patients was significantly impaired. These findings may indicate that OCD patients manifest abnormal aspects of second pass-parsing processes of information processing as they are reflected by P600 amplitudes and latencies.

Adult↗